WO2000038974A1

WO2000038974A1 - Device for disengaging buoys and transponders from submarine pipelines

Info

Publication number: WO2000038974A1
Application number: PCT/IT1999/000419
Authority: WO
Inventors: Giorgio S. Danieli; Paolo Pio Danieli
Original assignee: Danieli, Giovanna
Priority date: 1998-12-23
Filing date: 1999-12-23
Publication date: 2000-07-06
Also published as: IT1305742B1; ITCS980017A1

Abstract

The present invention is relative to a telecommanded device to disengage buoys and transponders that are positioned on submarine pipelines during their laying. At present in fact such buoys are positioned on the pipe in pre established positions and fixed to it with metallic or kevlar straps, in order to subtract buoyancy forces to the weight, thereby reducing vertical loads. Similarly, also transponders are positioned on the pipe to allow identifying pipe position when needed. However, once the pipe layed has reached the sea bed, it is necessary to detach the buoys, to give greater stability to the pipe, and this work is performed by an R.O.V. (Remotely Operated Vehicle) that, following the pipe, cut the straps one at the time. Similarly once the laying is completed, also the transponders, used to identify some peculiar portions of the pipe, can be detached, and this operation is again performed by an R.O.V. The present invention is therefore relative to a device containing both a radio able to receive and transmit under water, or a circuit which can be remotely activated in some way, and a disengagement mechanism. This device (1) must itself be fixed to the buoy using straps (2) or any other mean, and must contain contain an hydraulic or spring loaded or explosion acted mechanism that causes the cutting or unfastening of the straps connecting the buoy (3) or the transponder to the pipe, so that the buoy, or the transponder, helped in this case by a small service buoys, are free to surface the sea to be reutilized.

Description

DEVICE FOR DISENGAGING BUOYS AND TRANSPONDERS FROM SUBMARINE PIPELINES

Background of the Invention:

1. Field of the Invention

During submarine pipeline laying it is often necessary to position plastic buoys in order to reduce vertical loads on pipes thereby reducing stesses. However, once the buoy has reached the sea bed, it is necessary to eliminate the buoys, that can cause instability of the pipeline.

Similarly, it is sometime necessary to position submarine trasponders to identify a particular section of the pipeline, once layed down. Also in this case the transponders are strapped to the pipe, and must be removed once the laying operation is completed.

2. Description of Prior Art This task is performed by an RON. (Remotely Operated Vehicle) that goes to cut the straps connecting the pipeline to the buoy, that will surface and may be reused. Similarly, the RON. can cut the straps connecting the transponder to the pipe, and can recuperate it. The problem is the fact that the RON. cost is extremely high. Summary of the Invention The present invention is relative to a disengagement device that can be part of the buoy or can be independent from it, containg both a coded remote control able to receive ultrasound signals or other types of control, as discussed later, and a mechanism that either estract blades to cut the straps, or self explosive bolts, or a mechanism similar to baggage or trunk locks, spring or explosion actuated. Νaturallly the spring loaded device must be pro-loaded and blocked before usage by a tooth that will be removed by remote control, unlocking the system, and allowing buoy's disengagement, emersion and recovery. Obviously the remote control may also be activated mechanically, or though a signal sent through a wire or through the pipe itself.

A similar device can be used, coupled to smaller size buoys, to recuperate also the transponders that are sometimes strapped to the pipe. In this case, the device can also be integrated with the transponder, that will be used as a two way submarine radio. Brief Description of the Drawings. Passing to the description of the Figures, Figure I shows a possible execution of the device, on which four slots used to strap the device to the buoy are present. Notice that one of the extremes is bulkier to host the remote control, its battery, the cutting blade ready to use, together with the unlocking mechanism, that can be actuated via solenoid, or by a chemical reaction (explosion).

The following Figure 2 shows a possible version of the device in which the pre-loaded spring acts on a rigid stucture connecting two wedges, causing with their displacement the exit of the blades and the cutting of the straps connecting the buoy to the pipe. Passing to Figure 3, the device presents on one side self explosive bolts which are holding the straps through a simple slot, while on the other side a similar device is blocked by an open hook, that is freed by the explosion of the bolts. Figure 4 shows the device in a simpler and more economic version in which the self exploding bolts are substituited by a lock very similar to those utilized for closing luggages and trunks, and where the preloading mechanism can be a spring or explosive. Figure 5 shows the device fixed to the buoy with straps, while the following shows device and buoy fixed to the pipe.

Figure 7 shows the disengagement phase during which the blades are cutting the straps, while the following 8 and 9 show the "animation" of the disengagement phase in the last two versions of the device. Description of Preferred Embodiment.

The preferred embodiement is based on a mechanism which on one side presents an open slot in which the bolts used to tend the straps are located. On the other side a mechanism similar to a car trunk lock has been used, presenting a special shape that, at opening, not only frees the end ring, but also pushes it out of the slot, ensuring the unlocking process. This is shown in Figure 10.

For instance, in the measuring device used in the research that led to the present Patent Application (Figure 2), the six degrees of freedom are all rotational, but allow as well placing the two bodies in any reciprocal position. Similarly the six degrees of freedom of both the measuring device and the two fixator's portions can be set as described in US Patent n° 5,152,280 (Figure 3), or in any other configuration, as long as at least three rotational degrees are left.

Claims

1) Device for disengagement of buoys from submarine pipes, characterized by the presence of a disengagement system made by one or two spring loaded blades used to cut the straps connecting the buoy to the pipe under remote control

2) Device for disengagement of buoys from submarine pipes, characterized by the presence of a disengagement system made by one or two explosive activated blades used to cut the straps connecting the buoy to the pipe under remote control

3) Device for disengagement of buoys from submarine pipes, characterized by the presence of a disengagement system made by one or two hydraulically activated blades (using water pressure) used to cut the straps connecting the buoy to the pipe under remote control

4) Device for disengagement of buoys from submarine pipes, characterized by the presence of a disengagement system made on one side by an open hook or slot, to which the straps are connected, while on the other are placed self exploding bolts that, under remote control, will distroy themselves 5) Device for disengagement of buoys from submarine pipes, characterized by the presence of a disengagement system made on one side by an open hook or slot, to which the straps are connected, while on the other are is connected a basculating hook that, under remote control, will open itself being activated by a spring or by a small explosion, freeing the buoy 6) Device for disengagement of buoys from submarine pipes, in which the remote control and the actuator are separated, being the first recovered with the buoy, while the actuator will remain on the sea bed 7) Buoy containg one of the aforementioned mechanisms.